13 STRUCTURE AND BIOLOGICAL ACTIVITY OF DISCADHNINE, A SPORE GERMINATION INHIBITOR FROM THE CELLULAR SLIME MOLD
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Spore germination of D. discoideum is regulated by a germination inhibitor as a self-inhibitor. In the course of the studies on the inhibitor of this organism, the ethanolic extract of spores collected from twenty thousands Petri plates was separated by dialysis, chromatography on Amberlite XAD-2 resin and Sephadex LH-20 gel to Provide the inhibitor (about 15mg) named discadenine. Color reactions, UV and MS spectral analyses indicated that discadenine is 6-(3-methyl-2-butenylamino)purine substituted on α-amino acid at the 3-position of the purine ring. Based on the ^<13>C-NMR and the proton-coupled spectral analyses compared with a model compound, 3-methyl-6-(3-methyl-2-butenylamino)purine, the structure of discadenine was elucidated as 3-(3-amino-3-carboxypropyl)-6-(3-methyl-2-butenylamino)purine. Starting from 6-(3-methyl-2-butenylamino)purine, (±)-discadenine was synthesized. The synthetic discadenine was identical with the natural sample on chromatographic and spectral behavior. Besides its pronounced spore germination inhibitory activity (100% inhibition at 10^<-7>M), discadenine exhibits significant cytokinin activity (approximately one-sixth level of kinetin) in the standard tobacco pith test.
